Silicon nanowires are widely used in high-speed and highly-integrated electrical components and sensors. When silicon nanowires have a diameter of 10 nm or less, a quantum confinement effect occurs and thus, quick charge transfer is possible. According to the conventional art, silicon nanowires are grown on a substrate mainly using a metal catalytic layer.
FIGS. 1 through 3 are cross sectional views illustrating a conventional method of manufacturing silicon nanowires.
Specifically, a metal catalytic layer 12, for example, a gold (Au) layer, is deposited on a substrate 10 (FIG. 1). Then the metal catalytic layer 12 is converted into catalytic metal islands 14. The catalytic metal islands 14 are self-formed at a high temperature in a nanowire growth apparatus used in a later process, for example, a thermal chemical vapor deposition apparatus. The diameter of the self-formed catalytic metal islands 14 is large, in the order of tens of nm, for example, 20 nm or larger and the areal density (number of catalytic metal islands 14 per unit area) thereof is very low, that is, 1010/cm2 (FIG. 2).
Next, a silicon source is provided to a growth apparatus for growing silicon nanowires and silicon nanowires 16 are grown on the substrate 10 using the catalytic metal islands 14 as a catalyst. The catalytic metal islands 14 support crystal growth in the silicon nanowires 16. According to the size (diameter) of the catalytic metal islands 14, the size (diameter) of the silicon nanowires 16 is determined (FIG. 3).
A silicon integrated circuit which is included in CPU of computers or other electronic components is realized on a silicon substrate using electronic elements such as complementary metal-oxide-semiconductor (CMOS). A plurality of the silicon integrated circuits form one chip, and a plurality of the chips form a module. Signals are exchanged through metal wirings between the chips.
Since interconnection between the chips has been performed using metal wiring, the speed of signal processing has become rapid and the amount of transmitted and received information expressed by a band width has also increased rapidly. Thus along with the increasing speed of signal processing, several problems in integrated composite devices such as transmission speed, heat radiation, cross-talk, etc., have developed.
To solve the problems occurring when the chips are interconnected, application of an optical device has been suggested. Moreover, much research has been conducted on replacing optical devices formed expensive chemical compounds with cost-effective silicones. Consequently, universities, laboratories and industries have been successful in developing silicon optical devices and made them public. However, most silicon optical devices are developed as individual devices. In addition, the substrates used for the optical devices are not conventional bulk silicon substrates but mostly silicon-on-insulator (SOI) substrates.